1. Field of the Invention
The present invention relates to a novel Y zeolite catalyst, a method for preparation thereof and a method for preparation of monoisopropylnaphthalene and/or diisopropylnaphthalene using this Y zeolite catalyst. Particularly, the present invention relates to a catalyst containing a specific Y zeolite, and this catalyst makes possible the production of .beta.-monoisopropylnaphthalene in high yield by alkylation of naphthalene and the production of .beta.-monoisopropylnaphthalene and/or 2,6- and 2,7-diisopropylnaphthalenes in good yield by alkylation of naphthalene and/or monoisopropylnaphthalene in good percent conversion.
2. Description of the Prior Art
2,6- and 2,7-diisopropylnaphthalenes are useful as intermediates for preparation of polymers. Among them, 2,6-diisopropylnaphthalene can be utilized widely because 2,6-naphthalenedicarboxylic acid obtained by its oxidation is used as starting materials for synthesis of polyester (synthetic fiber and film).
A method for preparation of diisopropylnaphthalenes comprising alkylating naphthalene with propylene in the presence of Lewis acids such as AlCl.sub.3 to obtain monoisopropylnaphthalene and/or 2,6-and 2,7-diisopropylnaphthalenes is well-known. However, in this alkylation method, reaction products have to be separated from the catalyst after completion of the reaction. Further this method is not economical since the catalyst used has properties corroding a reaction apparatus.
Japanese Patent Disclosure (KOKAI) No. 51-56435 discloses a process for preparing isopropylnaphthalene comprising alkylation of naphthalene with propylene using a BF.sub.3 --H.sub.3 PO.sub.4 adduct catalyst instead of AlCl.sub.3.
However, the BF.sub.3 --H.sub.3 PO.sub.4 adduct catalyst has the same corrosive properties as AlCl.sub.3 has. Further, after completion of the reaction, isomerization of the resulting reaction products is necessitated because of the low selectivity of objective .beta.-monoisopropylnaphthalene.
On the other hand, Japanese Patent Publication (KOKOKU) No. 55-45533 discloses a method for preparation of .beta.-monoisopropylnaphthalene using a solid catalyst easily separable from reaction products, in which naphthalene is alkylated with propylene using an aluminum oxyhalide or a titanium oxyhalide as the catalyst. However, a large amount of high boiling point substances are produced and .beta.-monoisopropylnaphnaphthalene content based on total monoisopropylnaphthalene is low.
U.S. Pat. No. 4,026,959 discloses a process for increasing .beta.-monoisopropylnaphthalene content comprising isomerization of a mixture of isopropylnaphthalenes using a rare earth metal ammonium ion-exchanged Y zeolite.
Furthermore, Japanese Patent Disclosure No. 62-226931 discloses a process for preparation of diisopropylnaphthalene comprising alkylating naphthalene with propylene using silica-alumina or synthetic mordenite as the catalyst. However, the reaction temperature of this process is high (250.degree.-350.degree. C.) and the resulting diisopropylnaphthalene containing products have to be concentrated by repeating precision distillations in order to recover 2,6-diisopropylnaphthalene by crystalization since the content of 2,6-diisopropylnaphthalene in the products is low.
A method for alkylation of naphthalene and/or monoisopropylnaphthalene in good percent conversion by using a solid catalyst having a long activity life, particularly a method for preparing monoisopropylnaphthalene in good selectivity of .beta.-monoisopropylnaphthalene (high .beta.-isomer content) and a method for preparing 2,6- and 2,7-diisopropylnaphthalenes in good selectivity have not yet been established. Accordingly, an object of the present invention is to provide a catalyst useful for a method for preparation of mono and/or diisopropylnaphthalenes having a long activity life.
Another object of the present invention is to provide a method for preparation of mono and/or diisopropylnaphthalenes of which percent conversion of starting materials such as naphthalene and selectivity of .beta.-monoisopropylnaphthalene and 2,6- and 2,7-diisopropylnaphthalenes are good.
Further object of the present invention is to provide a catalyst capable of converting monoisopropylnaphthalene into 2,6-diisopropylnaphthalene in good selectivity.
Furthermore object of the present invention is to provide a catalyst capable of converting monoisopropylnaphthalene into 2,7-diisopropylnaphthalene in good selectivity in addition to 2,6-diisopropylnaphthalene.
The other object of the present invention is to provide a catalyst for preparation of diisopropylnaphthalene with a long activity life.